Management of Network Quality of Service

ABSTRACT

In one embodiment, a router is deployed on a local area network (LAN) in addition to any routers deployed on a wide area network (WAN) coupled with the LAN having the router. A service management device is coupled between the two routers. The service management device provides management processing, for example, quality of service (QoS) processing, traffic shaping, type of service (ToS) processing, or class of service (CoS) processing. For messages between devices both coupled to the WAN router, the WAN router diverts the messages to the LAN router. The LAN router then returns the messages back to the WAN router through the service management device, which provides management processing. The WAN router then forwards the processed message to the destination device.

FIELD

The invention relates to network management. More particularly, theinvention relates to techniques for managing quality of service ofnetwork traffic.

BACKGROUND

In current network architectures it is possible for traffic to passbetween interfaces of a single router without being processed by aquality of service (QoS) device. For example, as illustrated in FIG. 1,a message can pass from host 145 to host 155 in wide area network (WAN)100 without being processed by QoS device 110, which provides quality ofservice processing to WAN 100. A message generated by host 145 anddesignated for host 155 is sent through routers 140, 130 and 150 to host155. Only messages that pass from router 130 to QoS device 110 receivequality of service processing. That is, only messages that pass fromrouter 130 to local area network (LAN) 120 or from LAN 120 to router 130receive quality of service processing. Thus, the configuration of FIG. 1cannot guarantee quality of service processing for all messages.

Various solutions have been provided for this problem in the prior art.For example, traffic from router 140 and router 150 can be directed toQoS device 110 by separate links. This solution is expensive andprovides limited scalability. Simple Network Management Protocol (SNMP)can be used to communicate between QoS device 110 and router 130 to useexcess bandwidth provided by QoS device 110 to provide quality ofservice processing for messages that otherwise would not received QoSprocessing. However, this solution typically prioritizes WAN trafficover LAN-to-WAN traffic, which may not be appropriate.

A WAN-based quality of service device can be used. However, the benefitsof quality of service devices are significantly reduced when QoS device110 is deployed on the WAN side of router 130 because the primarycongestion point exists from the LAN to the WAN, which is not addressedin this configuration.

SUMMARY

Methods and apparatuses for management of network quality of service aredescribed. In one embodiment, the present invention includes thefollowing. A first network device, for example a router receives messagefrom remote devices. An identifier that indicates the source of themessage is associated with the message. The message is passed to asecond network device, for example another router. The second networkdevice modifies the identifier to indicate a destination of the message.Quality of service processing is performed for the message based on theidentifier associated with the message. In one embodiment, theidentifier is a Differentiated Services Code Point (DSCP) that istransmitted as part of the message header. In one embodiment, quality ofservice processing (or other types of processing) can be performed onmessages as the messages pass from the WAN router to the LAN router.This processing can be performed in addition to, or in place of,processing that is performed on messages as they pass from the LANrouter to the WAN router.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated by way of example, and not by way oflimitation, in the figures of the accompanying drawings in which likereference numerals refer to similar elements.

FIG. 1 is one embodiment of a prior art network configuration in whichquality of service processing is not guaranteed for all messages.

FIG. 2 is one embodiment of a network configuration in which servicemanagement processing is provided for WAN-to-WAN traffic with a LANrouter.

FIG. 3 is a block diagram of one embodiment of an electronic system thatcan be used for providing identifiers for quality of service processing.

FIG. 4 is a flow diagram of a process in which quality of serviceprocessing is provided for WAN-to-WAN traffic with a LAN router.

FIG. 5 illustrates an Internet Protocol header having a DSCP field thatcan be used in quality of service processing.

DETAILED DESCRIPTION

Management of network services is described. In the followingdescription, for purposes of explanation, numerous specific details areset forth in order to provide a thorough understand of the invention. Itwill be apparent, however, to one skilled in the art that the inventioncan be practiced without these specific details. In other instances,structures and devices are shown in block diagram form in order to avoidobscuring the invention.

In one embodiment, a router is described on a local area network (LAN)in addition to any routers deployed on a wide area network (WAN) coupledwith the LAN having the router. A service management device is coupledbetween the two routers. The service management device can be any typeof device that provides network management services on network traffic.The service management device can be, for example, a gateway, a routeror any other provide network node.

The service management device provides management processing, forexample, quality of service (QoS) processing, traffic shaping, type ofservice (ToS) processing, or class of service (CoS) processing. Formessages between devices both coupled to the WAN router, the WAN routersends the messages to the LAN router. The LAN router then routes themessages back to the WAN router through the service management device,which provides management processing. The WAN router then sends theprocessed message to the destination device.

FIG. 2 is one embodiment of a network configuration in which servicemanagement processing is provided for WAN-to-WAN traffic with a LANrouter. While the example of FIG. 2 includes four routers, any number ofrouters can be supported and used to provide the service managementprocessing described herein.

Network device 245 generates a message to be transmitted to networkdevice 255. Network devices 245 and 255 can be any type of networkdevices for example, computer systems, printers, personal digitalassistants (PDAs), etc. The message can be any type of message in anytype of network formal. For example, the message can be an InternetProtocol (IP) packet, which is variable in length, or an AsynchronousTransfer Mode (ATM) cell, which is a fixed length. Network device 245sends the message to router 240.

Router 240 analysis the message to determine the routing path andforwards the message to router 230 through WAN-to-WAN interface 220.Router 230 receives the message and analyzes the message to determine arouting path to the destination. Because management services device 270is not coupled between router 230 and the destination, network device255, management service processing (e.g., QoS processing) would not beperformed if the message were directly routed to network device 255.

In order to provide management service processing, router 230 routes themessage to router 200. Router 200 then sends the message back to router230. By sending the message to router 200 when the message would nototherwise be sent to router 200 or any device on the network that wouldcause the message to pass through management services device 270management services can be provided.

In general, routers that are part of a WAN (or other type of network)are coupled with other routers on the WAN. The connections between theserouters are referred to as WAN-to-WAN interfaces (e.g., 220, 230).Management services devices are often deployed on a LAN side of a routerand the interface between the router and the LAN devices (including themanagement services device) is referred to as a WAN-to-LAN interface(e.g., 210). By sending messages through a management services device toa router that would not normally be on the pant of a message and thensending the message back to the otherwise normal path for the message,management services processing can be provided to messages that wouldnot otherwise be processed.

In one embodiment, when router 230 receives a message from networkdevice 245 to network device 255, router 230 modifies the DifferentiatedServices Code Point (DSCP) in the header of the message to correspond tothe source of the message. The message is then sent to router 200through management services device 270.

In general, Differentiated Services (DiffServ or DS) is a protocol forspecifying and controlling network traffic by class so that certaintypes of traffic get precedence, for example, voice traffic, whichrequires a relatively uninterrupted flow of data, might get precedenceover other kinds of traffic. Differentiated Services use a policy orrule statements to determine how to forward a given network packet. Fora given set of forwarding behaviors, known as per hop behaviors (PHBs),a six-bit field (the DSCP), in the Internet Protocol header, specifiesthe per hop behavior for a given flow of packets.

Note that the use of the DSCP field for QoS or other management serviceprocessing is different than prior use of DSCP. Thus, an existing fieldin an IP header can be used for a non-intended purpose (i.e., to providerouting information that can be used for QoS processing) to provideimproved management service processing. In alternate embodiments,techniques other than use of the DSCP field can be used. Any techniquein which uses source and destination identifiers and the concept ofinbound and outbound traffic can route messages as described herein toprovide improved management services processing.

In one embodiment, when router 200 receives a message from router 230,router 230 modifies the DSCP of the message to correspond to thedestination of the message and sends the message back to router 200through management services device 270. Management services device 270provides quality of service processing on the message based on thedestination of the message. Service management device 270 can alsoperform traffic shaping processing, class of service processing, type ofservice processing, and/or any other type of network policy processing.

In one embodiment, management services device 270 provides quality ofservice processing on messages that pass between router 230 and router200. The quality of service processing can be performed on messages thatpass in one direction (i.e., from router 230 to router 200 or router 200to router 230) or on messages that pass in both directions. Quality ofservice processing can be performed in any manner Known in the art.Router 230 then forwards the message to router 250, which forwards themessage to network device 255.

In one embodiment, the routers, network devices and/or quality ofservice processor of FIG. 2 can be implemented as an electronic systemsthat executes sequences of instructions. The sequences of instructionscan be stored by the electronic device or the instructions can bereceived by the electronic device (e.g., via a network connection). FIG.3 is a block diagram of one embodiment of an electronic system that canbe used for providing identifiers for quality of service processing. Theelectronic system illustrated in FIG. 3 is intended to represent a rangeof electronic systems, for example, computer systems, network accessdevices, routers, hubs, switches, etc. Alternative systems, whetherelectronic or non-electronic, can include more, fewer and/or differentcomponents.

Electronic system 300 includes bus 301 or other communication device tocommunicate information, and processor 302 coupled to bus 301 to processinformation. While electronic system 300 is illustrated with a singleprocessor, electronic system 300 can include multiple processors and/orco-processors. Electronic system 300 further includes random accessmemory (RAM) or other dynamic storage device 304 (referred to asmemory), coupled to bus 301 to store information and instructions to beexecuted by processor 302. Memory 304 also can be used to storetemporary variables or other intermediate information during executionof instructions by processor 302.

In one embodiment, memory 304 includes operating system 390, whichprovides software control of hardware components of electronic system300. Any type of operating system known in the art appropriate forelectronic system 390 can be used. Memory 304 can also storeapplication(s) 398, which represent one or more applications that can beexecuted by processor(s) 302.

In one embodiment, memory 304 includes management services agent 392. Inalternate embodiments, management services agent 392 can be stored inROM 306, implemented as hardware, or as any combination of hardware andsoftware. In general, management services agent 392 provides thefunctionality described herein to route messages through a managementservices device (e.g., management services device 250 of FIG. 2).

If electronic device 300 is a WAN router, management services agent 392analyzes an incoming message to determine whether the message should berouted to a LAN router in order to provide management servicesprocessing. In one embodiment, management 392 analyzes the header of themessage to determine the source of the message. Management servicesagent 392 then causes the DSCP field in the header of the message to bemodified to indicate the source of the message.

If electronic device 300 is a LAN router, management services agent 392analyzes an incoming message to determine whether the message is fromthe WAN router and whether the message should be routed back to the WANrouter. If so, management services agent 392 modifies the DSCP field toindicate the destination of the message and sends the message back tothe WAN router through a management services device. The managementservices device provides QoS (and/or other) processing on the message.

Electronic system 300 also includes read only memory (ROM) and/or otherstatic storage device 306 coupled to bus 301 to store static informationand instructions for processor 302. Data storage device 307 is coupledto bus 301 to store information and instructions. Data storage device307 such as a magnetic disk or optical disc and corresponding drive canbe coupled to electronic system 300.

Electronic system 300 can also be coupled via bus 301 to input/output(I/O) devices 310, such as, for example, a cathode ray tube (CRT) orliquid crystal display (LCD), to display information to a user, akeyboard, a mouse, a trackball, or cursor direction keys to communicatedirection information and command selections to processor 302.Electronic system 300 further includes network interfaces 320 to provideaccess to a network, such as a local area network.

Instructions are provided to memory from a storage device, such asmagnetic disk, a read-only memory (ROM) integrated circuit, CD-ROM, DVD,via a remote connection (e.g., over a network via network interface 320)that is either wired or wireless providing access to one or moreelectronically-accessible media, etc. In alternative embodiments,hard-wired circuitry can be used in place of or in combination withsoftware instructions. Thus, execution of sequences of instructions isnot limited to any specific combination of hardware circuitry andsoftware instructions.

An electronically-accessible medium includes any mechanism that provides(i.e., stores and/or transmits) content (e.g., computer executableinstructions) in a form readable by an electronic device (e.g., acomputer, a personal digital assistant, a cellular telephone). Forexample, a machine-accessible medium includes read only memory (ROM);random access memory (RAM); magnetic disk storage media; optical storagemedia; flash memory devices; electrical, optical, acoustical or otherform of propagated signals (e.g., carrier waves, infrared signals,digital signals); etc.

FIG. 4 is a flow diagram of a process in which quality of serviceprocessing is provided for WAN-to-WAN traffic with a LAN router.Messages are sent from a source network device to a WAN router, 400. Thedestination network device is also coupled to the same WAN routerthrough a different port than the source network device. Any number ofrouters or other network components can be coupled between the sourcenetwork device and the WAN router as well as between the WAN router andthe destination network device.

The WAN router generates an indication of the source or the message,410. In one embodiment, the WAN router modifies a DSCP field in theheader of the message to indicate the source network device. Otherindicators can also be used. The WAN router sends the message to a LANrouter, 420. In one embodiment, the message is sent to the LAN routerthrough a quality of service device or other network management device.In an alternate embodiment, the message passes through the quality ofservice device only on its return to the WAN router.

In one embodiment, quality of service processing (or other types ofprocessing) can be performed on messages as the messages pass from theWAN router to the LAN router. This processing can be performed inaddition to, or in place of, processing that is performed on messages asthey pass from the LAN router to the WAN router.

The LAN router changes the indicator (e.g., the DSCP field) to indicatethe destination network device, 430. The LAN router sends the message tothe quality of service device, which performs quality of serviceprocessing on the message, 440. The message is returned to the WANrouter 450. The message is sent to the destination network device, 460,in accordance with the quality of service parameters provided by thequality of service device.

FIG. 5 illustrates an Internet Protocol header having a DSCP field thatcan be used in quality of service processing. In general, packet 500includes header 520 and data portion 530, each of which can have anynumber of bits or bytes depending on the network protocol being used. Inone embodiment, header 520 includes DSCP field 510 that can be used asdescribed herein to provide network management services. In oneembodiment, DSCP field 510 is six bits; however, any number of bits canbe used. In alternate embodiments, fields other than DSCP field 510 canbe used in the manner described herein.

Reference in the specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the invention. The appearances of the phrase “in one embodiment” invarious places in the specification are not necessarily all referring tothe same embodiment.

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes can be made thereto withoutdeparting from the broader spirit and scope of the invention. Thespecification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense.

1. In a network environment comprising a first host, a second host, afirst network device, a second network device, and a QoS device, amethod allowing the QoS device to operate on packet flows transmittedbetween hosts, the method comprising: receiving, at the first networkdevice, a packet transmitted from the first host and addressed to thesecond host, wherein the packet comprises a header including a pluralityof header fields; diverting the packet from a routed communication pathbetween the first and second hosts by transmitting the packet from thefirst network device to the second network device, wherein the secondnetwork device is disposed out of the routed communication path;receiving, at the first network device, the packet from the secondnetwork device; and forwarding the packet from the first network devicealong the routed communication path to the second host; wherein duringdiverting the packet, the packet traverses the QoS device therebyenabling the QoS device to provide quality of service processing for thepacket, wherein the QoS device is disposed between the first and secondnetwork devices, and wherein the QoS device is located outside of therouted communication path between the first and second hosts.
 2. Themethod of claim 1 wherein the first network device is a first router andthe second network device is a second router.
 3. The method of claim 2wherein the packet is transmitted to the first router from a sourcerouter coupled with the first router and the packet is forwarded to adestination router coupled to the first router.
 4. The method of claim 1wherein the first network device is a WAN router, and the second networkdevice is a LAN router.
 5. A system comprising: a first network deviceoperably coupled to a routed path between a source host and adestination host, the first network device operative to receive, fromthe source host, a packet addressed to the destination host; a secondnetwork device coupled to the first network device by a second pathoutside the routed path to receive the packet from the first networkdevice; and a quality of service device coupled to the second pathbetween the first network device and the second network device toreceive the message when transmitted between the first and secondnetwork devices, and to perform quality of service processing on themessage; wherein, in response to receiving the packet from the sourcehost, the first network device is operative to divert the packet fromthe routed path along the second path to the second network device,receive the packet returned from the second network device, and forwardthe message to the destination host; wherein during diversion of thepacket, the packet traverses the QoS device thereby enabling the QoSdevice to provide quality of service processing for the packet.
 6. Thesystem of claim 5 wherein the first network device is a first router andthe second network device is a second router.